1. Field of the Invention
This application relates to antenna systems used with passive or active sensors and in particular relates to antenna array systems and protocols used in Radio Frequency Identification (RFID) system base station and sensory networks.
2. Background of the Invention
An RFID system conventionally includes a set of stationary or mobile RFID tags located within a physical area readable by a base station reader. Each sensor may be passive or active, with or without battery. In conventional systems, the reader and the RFID tags are generally required to be in close proximity so that the tags can operate in close proximity to the reader antenna. The limited transmission distances available with conventional RFID systems limits their use in an automated factory setting, and/or in an indoor wireless environment. Even within in the designed range of operation, such systems often have low reliability due to interferences and collisions.
If an RFID system covers a large enough area, multiple base stations may be necessary to provide adequate coverage for the area. In addition, bandwidth usage may be high because the base station computer must communicate with and process information from every radio tag within its operational range. The lack of available bandwidth limits the ability of a base station interacting with more than one radio tag at any given time.
What is needed is an RFID system without such limitations.